Based on prior knowledge, calcium channel blockers are commonly used to treat chronic heart failure. Therefore, it is likely that patients who have chronic heart failure would have used calcium channel blockers in the ICU. 

To analyze the relationship between the feature ANT_CA_S_n and the presence of chronic heart failure, we can examine the distribution of ANT_CA_S_n values for patients with and without chronic heart failure:

- If there is a high proportion of patients with chronic heart failure among those who used calcium channel blockers (ANT_CA_S_n = 'yes'), it suggests a positive relationship between the feature and the target class 'yes'.
- If there is a low proportion of patients with chronic heart failure among those who did not use calcium channel blockers (ANT_CA_S_n = 'no'), it suggests a negative relationship between the feature and the target class 'yes'.

Based on this analysis, we can create the following dictionary:

```json
{
	"no": ["no"], 
	"yes": ["yes"]
}
```

This dictionary indicates that the target class 'no' is associated with the feature value 'no', and the target class 'yes' is associated with the feature value 'yes'.